1. Technical Field
This invention relates generally to posts, and more particularly to an apparatus and methodology for driving a flexible post into the ground.
2. Background Information
A flexible post tends to buckle and bend when driven, thereby making installation difficult. It does so all the more when the particular application couples stringent flexibility requirements with installation in hard ground. Nevertheless, flexible posts enjoy widespread use so that the tools and methodology utilized for their installation demand attention.
Consider, for example, a flexible post of the type commonly utilized along the highway. Sometimes called a flexible, highway-delineator guidepost or just guidepost, it may be used to mark such things as the highway edge, the shoulder, or an object or feature of the terrain along the highway. In addition, it may be fabricated and installed according to governmental specifications.
In that regard, typical guidepost specifications such as those issued by CALTRANS of the State of California may require that the guidepost be about five and one-half feet long so that eighteen inches can be driven into the ground with the other four feet remaining above ground. The guidepost specifications may also require that the guidepost be installable by driving it into the ground without the need for a separately prepared pilot hole (i.e., a separate hole-forming tool and hole-forming operation) and that when installed the guidepost be capable of enduring ten hits by an automobile traveling at fifty-five miles-per-hour without failing to come back to within twenty degrees of a vertical position.
Some existing drivers for such guideposts take the form of a conventional fence post driver, employing a heavy steel sleeve that fits telescopingly over the post. The sleeve has an open lower end and a closed upper end, the installer first placing the driver over the guidepost so that the closed end of the sleeve rests upon the upper end of the guidepost and then putting the guidepost in a vertical position where it is to be installed. Next, the installer slides the driver upwardly. Then he slams it downwardly so that the closed end impacts the upper end of the guidepost, the impact driving the guidepost downwardly into the ground.
But installing the guidepost in that manner can damage it. For example, the impact of the driver can cause the guidepost to bend and buckle. In addition, the guidepost may deform sufficiently to get stuck in the driver. Furthermore, since four feet of the guidepost must remain above ground, the driver cannot be more than four feet long and it is usually even shorter. As installation begins, the lower portion of the guidepost is completely uncontained just above ground level so that a failure may result all the more easily. Thus, it is desirable to have a better way of driving a flexible post into the ground.